Description: The objective of this project is to determine if a combination of MRI and MRS can be used to separate participants with mild DAT from normal elderly controls by looking for focal neuronal loss, especially in the hippocampus. MRI will be used to examine brain focal atrophic changes in the hippocampus, and the MRS will be used to detect biochemical evidence of neuronal loss in the hippocampal region, as well as for more generalized loss in the frontal and parietal lobes. Hippocampal volume loss and shape deformation will be used to look for subtle regional changes in the contours of the hippocampus. Hippocampal body deformations will be related to changes in its internal architecture. As part of the internal analysis, the investigators will measure the gray matter in CA1 of the cornu ammons. MRS will be used to examine the frontal, parietal, and temporal lobes for regional neuronal loss by calculating N-acetylaspartate/creatine ratios. They also plan to conduct a longitudinal study to evaluate the evolution of both the morphometric and biochemical changes that occur during the course of this study. MRI and MRS hippocampal measurements will be compared to neuron and senile plaque counts performed by the Neuropathology Core in patients who are autopsied during the course of this study. This comparison will be extended to regions in the frontal and parietal lobes where the neuropathology core also obtains samples study.